JIT: Extend escape analysis to account for arrays with non-gcref elements

src/coreclr/jit/gentree.h

@@ -7458,12 +7458,11 @@ struct GenTreeArrAddr : GenTreeUnOp
 
 public:
     GenTreeArrAddr(GenTree* addr, var_types elemType, CORINFO_CLASS_HANDLE elemClassHandle, uint8_t firstElemOffset)
-        : GenTreeUnOp(GT_ARR_ADDR, TYP_BYREF, addr DEBUGARG(/* largeNode */ false))
+        : GenTreeUnOp(GT_ARR_ADDR, addr->TypeGet(), addr DEBUGARG(/* largeNode */ false))
         , m_elemClassHandle(elemClassHandle)
         , m_elemType(elemType)
         , m_firstElemOffset(firstElemOffset)
     {
-        assert(addr->TypeIs(TYP_BYREF));
         assert(((elemType == TYP_STRUCT) && (elemClassHandle != NO_CLASS_HANDLE)) ||
                (elemClassHandle == NO_CLASS_HANDLE));
     }

src/coreclr/jit/importer.cpp

@@ -9533,9 +9533,22 @@ void Compiler::impImportBlockCode(BasicBlock* block)
                 // Remember that this function contains 'new' of an SD array.
                 optMethodFlags |= OMF_HAS_NEWARRAY;
 
+                // We assign the newly allocated object (by a GT_CALL to newarr node)
+                // to a temp. Note that the pattern "temp = allocArr" is required
+                // by ObjectAllocator phase to be able to determine newarr nodes
+                // without exhaustive walk over all expressions.
+                lclNum = lvaGrabTemp(true DEBUGARG("NewArr temp"));
+
+                impStoreToTemp(lclNum, op1, CHECK_SPILL_NONE);
+
+                assert(lvaTable[lclNum].lvSingleDef == 0);
+                lvaTable[lclNum].lvSingleDef = 1;
+                JITDUMP("Marked V%02u as a single def local\n", lclNum);
+                lvaSetClass(lclNum, resolvedToken.hClass, true /* is Exact */);
+
                 /* Push the result of the call on the stack */
 
-                impPushOnStack(op1, tiRetVal);
+                impPushOnStack(gtNewLclvNode(lclNum, TYP_REF), tiRetVal);
 
                 callTyp = TYP_REF;
             }

src/coreclr/jit/jitmetadatalist.h

@@ -76,6 +76,8 @@ JITMETADATAMETRIC(NewRefClassHelperCalls,                int,              0)
 JITMETADATAMETRIC(StackAllocatedRefClasses,              int,              0)
 JITMETADATAMETRIC(NewBoxedValueClassHelperCalls,         int,              0)
 JITMETADATAMETRIC(StackAllocatedBoxedValueClasses,       int,              0)
+JITMETADATAMETRIC(NewArrayHelperCalls,                   int,              0)
+JITMETADATAMETRIC(StackAllocatedArrays,                  int,              0)
 
 #undef JITMETADATA
 #undef JITMETADATAINFO

src/coreclr/jit/lclmorph.cpp

@@ -826,6 +826,74 @@ class LocalAddressVisitor final : public GenTreeVisitor<LocalAddressVisitor>
 
         switch (node->OperGet())
         {
+            case GT_INDEX_ADDR:
+            {
+                assert(TopValue(2).Node() == node);
+                assert(TopValue(1).Node() == node->gtGetOp1());
+                assert(TopValue(0).Node() == node->gtGetOp2());
+
+                if (node->gtGetOp1()->OperIs(GT_LCL_VAR, GT_LCL_ADDR) && node->gtGetOp2()->IsCnsIntOrI())
+                {
+                    if (TopValue(1).IsAddress() &&
+                        m_compiler->lvaGetDesc(TopValue(1).LclNum())->GetLayout()->IsBlockLayout())
+                    {
+                        ssize_t offset = node->AsIndexAddr()->gtElemOffset +
+                                         node->gtGetOp2()->AsIntCon()->IconValue() * node->AsIndexAddr()->gtElemSize;
+
+                        if (offset < static_cast<ssize_t>(m_compiler->lvaLclSize(TopValue(1).LclNum())))
+                        {
+                            if (FitsIn<unsigned>(offset) &&
+                                TopValue(2).AddOffset(TopValue(1), static_cast<unsigned>(offset)))
+                            {
+                                INDEBUG(TopValue(0).Consume());
+                                PopValue();
+                                PopValue();
+                                break;
+                            }
+                        }
+                        else
+                        {
+                            GenTree* gtThrow =
+                                m_compiler->gtNewMustThrowException(CORINFO_HELP_RNGCHKFAIL, node->TypeGet(),
+                                                                    node->AsIndexAddr()->gtStructElemClass);
+                            m_compiler->lvaGetDesc(gtThrow->AsOp()->gtOp2->AsLclVarCommon())->incLvRefCnt(1, RCS_EARLY);
+                            *use           = gtThrow;
+                            m_stmtModified = true;
+                        }
+                    }
+                }
+
+                EscapeValue(TopValue(0), node);
+                PopValue();
+                EscapeValue(TopValue(0), node);
+                PopValue();
+                break;
+            }
+            case GT_ARR_LENGTH:
+            {
+                assert(TopValue(1).Node() == node);
+                assert(TopValue(0).Node() == node->gtGetOp1());
+
+                if (node->gtGetOp1()->OperIs(GT_LCL_VAR, GT_LCL_ADDR))
+                {
+                    if (TopValue(0).IsAddress() &&
+                        m_compiler->lvaGetDesc(TopValue(0).LclNum())->GetLayout()->IsBlockLayout())
+                    {
+                        GenTree* gtLclFld =
+                            m_compiler->gtNewLclFldNode(TopValue(0).LclNum(), TYP_INT, OFFSETOF__CORINFO_Array__length);
+                        SequenceLocal(gtLclFld->AsLclVarCommon());
+                        *use           = gtLclFld;
+                        m_stmtModified = true;
+                        INDEBUG(TopValue(0).Consume());
+                        PopValue();
+                        break;
+                    }
+                }
+
+                EscapeValue(TopValue(0), node);
+                PopValue();
+                break;
+            }
             case GT_STORE_LCL_FLD:
                 if (node->IsPartialLclFld(m_compiler))
                 {